[tests] Remove FAIL annotation from regress-336820

The test and associated bug have been fixed a while ago.

BUG=chromium:336820,v8:6325

Review-Url: https://codereview.chromium.org/2851343002
Cr-Commit-Position: refs/heads/master@{#45023}

test/mjsunit/mjsunit.status

@@ -130,9 +130,6 @@
   'compiler/alloc-number-debug': [PASS, ['mode == release', SKIP]],
   'regress/regress-634-debug': [PASS, ['mode == release', SKIP]],
 
-  # BUG(336820). TODO(bmeurer): Investigate.
-  'regress/regress-336820': [PASS, FAIL],
-
   # BUG(v8:2989). PASS/FAIL on linux32 because crankshaft is turned off for
   # nosse2. Also for arm novfp3.
   'regress/regress-2989': [FAIL, NO_VARIANTS, ['system == linux and arch == x87 or arch == arm and simulator == True', PASS]],